Phenoxido mediated antiferromagnetic and azide mediated ferromagnetic coupling in two dinuclear ferromagnetic nickel(ii) complexes with isomeric Schiff bases: a theoretical insight on the pathway of magnetic interaction

Two relatively rare mixed phenoxo and azide bridged dinuclear nickel(ii) complexes have been discussed. Both complexes show strong intermolecular hydrogen bonding interactions and exhibit ferromagnetic exchange coupling.

A 3D Cu(ii) tetrazolate coordination polymer based on pentanuclear units with a large coercive field

A 3D Cu(ii) coordination polymer with the ligand 1,2-bis(tetrazol-5-yl) exhibits spin-canting magnetic behavior with a large coercive field of 2.3 kOe.

Single-chain magnets assembled in cobalt(ii) metal–organic frameworks

This feature article discusses the advantages, progress and prospects of constructing single-chain magnets in metal–organic frameworks.

Mixed metal CoII1−xZnIIx–organic frameworks based on chains with mixed carboxylate and azide bridges: magnetic coupling and slow relaxation

A series of isomorphous three-dimensional metal–organic frameworks [Co^II_1−xZn^II_x(L)(N₃)]·H₂O (x = 0.26, 0.56 and 0.85) based on bimetallic Co^II_1−xZn^II_x (x = 0.26, 0.56 and 0.85) chains with random metal sites have been synthesized and magnetically characterized. The Co^II_1−xZn^II_x series, which intrinsically feature random anisotropic/diamagnetic sites, shows complex magnetic interactions. By gradually introducing the diamagnetic Zn^II ions into the pure anisotropic Co^II single-chain magnets system, the ferromagnetic interactions between Co^II ions are gradually diluted. Moreover, the slow magnetic relaxation behaviour of the mixed metal Co^II_1−xZn^II_x systems also changes. In this bimetallic series Co^II_1−xZn^II_x, the Co-rich materials exhibit slow relaxation processes that may arise from SCM mechanism, while the Zn^II-rich materials show significantly low slow magnetic relaxation. A general trend is that the activation energy and the blocking temperature decrease with the increase in diamagnetic Zn^II content, emphasizing the importance of anisotropy for slow relaxation of magnetization.

A series of mixed-metal systems consisting of Co^II_1−xZn^II_x chains with (μ-COO)₂(μ-EO-N₃) bridges were prepared, exhibiting interesting magnetic coupling and slow magnetic relaxation.

Random mixed-metal Co1−xNix single-chain magnets with simultaneous azide, carboxylate and tetrazolate bridges

A series of MOFs based on random ferromagnetic Co_1−xNi_x chains with simultaneous azide, carboxylate and tetrazolate bridges show metamagnetism and slow magnetic relaxation with complicated composition dependence and synergistic effects on single-chain slow dynamics.

Slow Magnetic Relaxation in Ladder-Type and Single-Strand 2p-3d-4f Heterotrispin Chains

Ladder-type and chain 2p-3d-4f complexes based on a bridging nitronyl nitroxide radical, namely, [LnCu(hfac)₅(NIT-Ph-p-OCH₂trz)]·0.5C₆H₁₄ [Ln = Y (1a), Dy (1b)] and [LnCu(hfac)₅(NIT-Ph-p-OCH₂trz)] [Ln = Y (2a), Dy (2b); NIT-Ph-p-OCH₂trz = 2-[4-[(1H-1,2,4-triazol-1-yl)methoxy]phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; hfac = hexafluoroacetylacetonate) have been successfully achieved through a one-pot reaction of the NIT-Ph-p-OCH₂trz radical with Cu(hfac)₂ and Ln(hfac)₃·2H₂O. Complexes 1a and 1b feature a ladder-like structure, where the rails are made of Ln(III) and Cu(II) ions alternatively bridged by nitronyl nitroxide and the triazole units while the NIT-Ph-p-OCH₂trz moieties act as the rungs of the ladder. Complexes 2a and 2b consist of one-dimensional nitronyl nitroxide bridged Ln coordination polymers with dangly Cu(II) units connected to the triazole moieties. All of compounds exhibit ferromagnetic NIT-Dy and/or NIT-Cu interactions. Both Dy derivatives (1b and 2b) show frequency-dependent out-of-phase magnetic susceptibility signals in a zero field indicating slow magnetic relaxation behavior.

Both end-on and end-to-end azide bridged tetranuclear ferromagnetic nickel(ii) Schiff base complexes

Variable temperature magnetic measurement of a tetranuclear nickel(ii) complex, consisting of two pseudo-dinuclear entities, indicates the presence of intra- and inter-dinuclear ferromagnetic interactions, corroborated by DFT calculations.

New complexes constructed from in situ nitration of (1H-tetrazol-5-yl)phenol: synthesis, structures and properties

New complexes based on three precursors via in situ nitration have been prepared. Moreover, the solid state UV-vis spectra and band gap energy of those complexes were investigated, and the luminescent properties (1–3, 7 and 8) and magnetic properties (3–6 and 9) were also discussed.

The structural diversity and properties of nine new viologen based zwitterionic metal–organic frameworks

A viologen based ligand has been explored as a functional building block to synthesize a series of nine new zwitterionic metal–organic frameworks with this contribution reporting on their structural, thermal and photochromic properties.

Composition dependence of magnetic relaxation for CoIIxNiII1−x chain-based compounds with mixed double azide–tetrazolate bridges

A series of isomorphous random bimetallic compounds based on CoIIxNiII1−x (0 ≤ x ≤ 1) chains with simultaneous azide–tetrazolate bridges exhibit composition-dependent magnetic relaxation were investigated.

Spin canting, metamagnetism, and single-chain magnetic behaviour in a cyano-bridged homospin iron(II) compound

Spin canting, antiferromagnetic ordering, metamagnetism and single-chain magnetism were verified in a cyano-bridged Fe(II) compound synthesized from the pentagonal bipyramidal Fe(II) starting material in the presence of excessive BF4(-) anions.

A new cube-based dodecanuclear cobalt(ii) cluster with azide and tetrazolate ligands exhibiting ferromagnetic ordering

A novel Co₁₂ cluster was composed of three identical Co₄ cubane units bridged by μ₆-CO₃²⁻ and tetrazolate bridges and exhibits long-range ferromagnetic ordering at about 9 K.

3D Co(ii) coordination polymer with ferrimagnetic-like layers based on azide and tetrazolate bridges showing slow magnetic dynamics

A novel layer-pillared 3D coordination polymer composed of unprecedented Co(ii) layers with azide and tetrazolate bridges exhibits the ferrimagnetic-like behaviors with spin-glass dynamic relaxation.

Assembly of organic–inorganic hybrid materials constructed from polyoxometalate and metal–1,2,4-triazole units: synthesis, structures, magnetic, electrochemical and photocatalytic properties

A family of organic–inorganic hybrids built by Keggin/Dawson POMs with metal–1,2,4-triazole units has been synthesized through modulating the pH value.

Spin-canting magnetization in 3D metal organic frameworks based on strip-shaped Δ-chains

Three 3D frameworks built from strip-shaped Δ-chains were prepared and magnetically characterized. The Cu(ii) compound shows spin canting, magnetic ordering and metamagnetism, while the Co(ii) and Ni(ii) compounds show canted antiferromagnetism.

First tetrazole-bridged d–f heterometallic MOFs with a large magnetic entropy change

The first example of tetrazole-bridged 3d–4f heterometallic MOFs {(H₃O)₃[Gd₃Mn₂(Trz)₄]·12H₂O}_n was obtained, exhibiting a large magnetic entropy change.

Construction of CuII Cluster-Based Magnetic Metal–Organic Framework Derived from a V-Shaped Aromatic Dicarboxylate Ligand

In our efforts towards rational design and systematic synthesis of cluster-based metal–organic frameworks, a new CuII coordination framework derived from the V-shaped aromatic dicarboxylate with formula [Cu4(µ4-O)(L)3]∞ (1), H2L = (4-phenyl)-2,6-bis(4-carboxyphenyl)pyridine) was synthesised under hydrothermal conditions and structurally characterised by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, and infrared spectroscopy. Structure analysis shows that complex 1 has a three-dimensional framework based on [Cu8] cluster with 8-connected bcu topology. Magnetic investigation suggests that anti-ferromagnetic coupling exists between CuII ions in the [Cu8] cluster.

Three new europium(III) methanetriacetate metal-organic frameworks: the influence of synthesis on the product topology

Three new metal-organic framework structures containing EuIIIand the little explored methanetriacetate (C7H7O63−, mta3−) ligand have been synthesized. Gel synthesis yields a two-dimensional framework with the formula [Eu(mta)(H2O)3]n·2nH2O, (I), while two polymorphs of the three-dimensional framework material [Eu(mta)(H2O)]n·nH2O, (II) and (III), are obtained through hydrothermal synthesis at either 423 or 443 K. Compounds (I) and (II) are isomorphous with previously reported GdIIIcompounds, but compound (III) constitutes a new phase. Compound (I) can be described in terms of dinuclear [Eu2(H2O)4]6+units bonded through mta3−ligands to form a two-dimensional framework with topology corresponding to a (6,3)-connected binodal (43)(466683)-kgdnet, where the dinuclear [Eu2(H2O)4]6+units are considered as a single node. Compounds (II) and (III) have distinct three-dimensional topologies, namely a (41263)(4966)-nianet for (II) and a (41065)(41164)-K2O2; 36641net for (III). The crystal density of (III) is greater than that of (II), consistent with the increase of temperature, and thereby autogeneous pressure, in the hydrothermal synthesis.

A perception of ferro- and antiferromagnetic interactions in a two dimensional Ni(ii) heterochiral coordination polymer showing unusual CO2 uptake behavior

A robust 2D heterochiral Ni(ii) coordination polymer is reported which shows ferro-, antiferromagnetic interactions and unusual CO₂ uptake behavior.

Novel Co-based metal-organic frameworks and their magnetic properties using asymmetrically binding 4-(4'-carboxyphenyl)-1,2,4-triazole

Two novel Co-based metal-organic frameworks (MOFs) were synthesised and characterised using an asymmetrically binding ligand, 4-(4'-carboxyphenyl)-1,2,4 triazole (Hcpt). The isolated [Co3(II)(μ3-O)(OH)(cpt)3(H2O)2]n·xH2O·yDMF, Co-MOF1, exhibits a rhombohedral crystal structure (space group, P63/mc), with a trinuclear cobalt core that resembles the MIL88 series. This MOF shows paramagnetic behaviour down to 2 K with no saturation of magnetisation up to 7 T. This is presumably due to a geometrically frustrated triangular arrangement of Co spins. The two-dimensional complex, [Co(II)(cpt)(N3)]n, Co-MOF2, crystallises in a monoclinic crystal system (space group, C2/m). The magnetic measurements reveal metamagnetic behaviour for this complex with a critical field in the range of 700-1000 Oe.

Three novel 1D lanthanide-carboxylate polymeric complexes: syntheses, crystal structures and magnetic analyses

Three novel one-dimensional (1D) lanthanide coordination complexes involving the 4-methyl-3-nitrobenzoic acid (HL) ligand, with the general formulae [Gd(L)3(H2O)(CH3OH)] (1), [Gd(L)3(H2O)2]·(4,4'-bpy)·CH3OH (2), [Dy(L)3(H2O)(CH3OH)] (3), have been synthesized by solvothermal reactions. These complexes have been structurally characterized by single-crystal X-ray diffraction, IR, PXRD, TGA, and elemental analysis. Complexes 1 and 3 are isostructural except for the distinction of the metal ion. Magnetic measurements indicate that complexes 1-3 show antiferromagnetic behaviors. Complex 3 behaves with slow relaxation of the magnetization, where the frequency-dependent out-of-phase signals are noticed. However, the characteristic maxima were not reached above 2 K under zero direct current (DC) fields. When a DC field of 5000 Oe was employed, the frequency dependent peaks of alternating current (AC) signals were obtained.

Slow magnetic relaxation in two new 1D/0D Dy(III) complexes with a sterically hindered carboxylate ligand

Two carboxylate-bridged Dy(III) complexes, [Dy(2)(piv)(5)(μ(3)-OH)(H(2)O)](n) (1) and [Dy(2)(piv)(6)(phen)(2)] (2) (pivH = pivalic acid; phen = 1,10-phenanthroline), have been synthesized and structurally characterized. Complex 1 takes a one-dimensional (1D) chain structure based on [Dy(4)(μ(3)-OH)(2)(piv)(8)(H(2)O)(2)](2+) units, while complex 2 is a dinuclear structure bridged by syn,syn-carboxylates. Magnetic investigation indicates weak ferromagnetic interaction between adjacent Dy(III) ions of the Dy(4) unit in 1 and weak intramolecular antiferromagnetic interaction between Dy(III) ions and/or depopulation of the Dy(III) excited-state Stark sublevels in 2. Alternating-current susceptibility measurements revealed frequency- and temperature-dependent out-of-phase signals under a zero direct-current field in 1, with typical slow magnetic relaxation behavior with an anisotropic barrier U ≈ 4.5 K, while 2 exhibits field-induced single-molecule-magnet behavior with ΔE/k(B) = 28.43 K under a 2 kOe external field.